Metal-coating process



Patented Apr. 14, 192% UNITED STATESTPATENT'Y OFFICE.

nosnnruv snoanma, or cinema, rumors, assronoa r0 LEADIZING conraw, or omcaeo, rumors, a ooitrona'rrorr or more I METAL-COATING raocnss.

rammin Original application filed April is, 1920, semi R0. 374,089'. innate hnd thil-lunlioaflon fled July 19,1920.

-To all'wlwm it may concem:

Illinois, have invented. certain new and useful Im rove'ments in- Metal-Coating Processes, 0 which the following is a specification.

M invention relates to the operation of coatin or plating metal articles, such, for exam e, as articles of iron or steel, with a suite le plating metal such as lead or tin; and the rimary object of the invention is to provide an improved plating process which will be simpler and more economical than the processes heretofore used and whereby the article may be plated or coated with a film of the coating metal which will be very thin but at the same time even,

homogeneous and non-porous. The thinness of the plating makes it ossible to plate articles such as threaded olts, and the like, the threading of which, with ordinary methods, would be filled u by the plating metal.

Other incidental ob ects will be mentioned in connection with the following descri tion of preferred methods of operation involving the principles of the invention.

A mixture is made of or more of a chloride of the platin metal, tin or lead, and 50% or less of zinc c oride. This mixture is heated to a temperature of about 600" Fahrenheit which produces a dissolving of the chlorides together and a disa'ssociation of the tin or lead chloride. The article to be plated is immersed in this solution, or if the article is hollow, the solution or its in redients may be laced and heated in such hollow article. T e tin or lead from the decomposed tin or lead chloride deposits on the surface with which the molten solution comes into contact, forming a thin, homogeneous, non-porous and very adherent coating or plating. The chemical action is one of substitution, iron from the article treated displacing .the lead or tin in the chloride because of the greater afiinity of the iron for the chlorine molecule in the sense of the followinge untion (assumin a lead plating operation) bCl,+Fe:Fe lg-t-Pb. The zinc chloride does not enter into the reaction. In lead plating the zinc chloride reduces materially the melting point of the solution,

'of lead chloride is very hi h., In

Serial No. 397,178.

whichis an advantage as tne meltm point tie case of a tln platin operat on t e zinc chloride keeps the solutioufrom volatilizing. When the article is removedfromjthe bath a certain amount of the tinor leadchloride' .will adhere tothe article, which, because of its iusolubility cannot be washed ofi as canthe zinc chlori e. The article is thereafter put into a vessel containing zinc chloride alone, of the plating surface brou ht into contact with the zinc chloride, which is heated to approximately 600 Fahrenheit. The chlor1 e of the lating metal will dissolve in the zinc chlori e at that temperature, and when the article is taken from the bath the salt thus formed may be washed oil with water. By this method it is possible to plate the inside alone of an article such as asheet metal can, boiler or a section of pipe. If the process iscarried on by, dippin the artic es into a molten bath, the metho 'has the advanta e over plating methods heretofore used tiatthe articles may be handled a considerable number at a time instead of singly ,The coating will be thinner and more even than that which results from the ordinary plat' method, the metal will penetrate into sma crevices, and, in general, the plating'will closel follow the surface of the article treated. rass or copper articles ma be plated by this method as well as articles of iron or steel. In carry' out this roc'ess the amount of the chlori e. of the p atin metal should not be substantially less than t e amount of the zinc chloride. If it is substantially less the lating will not be accomplished satisfactor y. This is due possibly to the solvent action. of the zinc chloride upon the metal deposited. The method is suitable for plating billets for cold drawing or stem ing in substitution for the common metho of doping.

If iron or steel articles are plated with nickel or cop er by the ordinary method of electrolysis, t e iron or steel in time will rust through the plating. This may be vented by first coating the article accor ing to the method above described with either tin or lead and then electroplating the article in the usual manner.

This application is a division of a application filed April 15, 1920, Sen

rior No 374,089 patented January 31, 1922 as No. 1,405,167

I claim:

1. Method of lating a metal article with lead or tin whic consists in subjecting the surface to be plated to contact with a molten bath containing a ,chloride of the plating metal capable of reacting with the metal to be plated to form a chloride of said metal to be plated and to roduce deposition on said surface of a t n, dense, adherent film of the plating metal, then bringin the plated surface into contact .with a so vent of the salt of the plating metal, at fusion temperature, and washing the article.

2. Method of plating an iron or steel article with a thin, adherent rust-proof film which consists in subjecting thesurface to be plated to contact with a chloride of the 20 plating metal and zinc chloride heated to fusion to produce substitution in the first named chloride of the plating for the plating metal and deposition of the plating metal on said surface, then bringing the plated surface into contact with the zinc chloride at fusing temperature to dissolve the adherent chloride of the plating metal.

3. Methud of plating a metal article which consists in bringing the surface to be plated into contact with a chloride of the plating metal and zinc chloride at a temperature of substantially 600 Fahrenheit to produce disassociation of the chloride of the plating metal and deposition of the plating metal on said surface, then bringing said plated surface into contact with zinc chloride heated to a temperature of substantially 600 Fahrenheit, and washing to remove the adherent salt.

ROBERT JAY SHOEMAKER.

374,089 Spatented January 31, 1922 as No. 1,405,167 a I claim:

1. Method of lating a metal article with lead or tin whic consists in subjecting the surface to be plated to contact with a molten bath containing a ,chloride of the platin metal capable of reacting with the meta to be plated to form a chloride of said metal to be plated and to roduce deposition on said surface of a t in, dense, adherent film of the plating metal, then bringin the plated surface into contact with a so vent of the salt of the plating metal, at fusion temperature, and washing the article.

2. Method of plating an iron or steel article with a thin, adherent rust-proof film which consists in subjecting thesurface to be plated to contact with a chloride of the plating metal and zinc chloride heated to fusion to produce substitution in the first named chloride of the plating for the plating metal and deposition of the plating metal on said surface, then bringing the plated surface into contact with the zinc chloride at fusing temperature to dissolve the adherent chloride of the plating metal.

3. Method of plating a metal article which consists in bringing the surface to be lated into contact with a chloride of the p ating metal and zinc chloride at a temperature of substantially 600 Fahrenheit to produce disassociation of the chloride of the plating metal and deposition of the plating metal on said surface, then bringing said plated surface into contact withzinc chloride heated to a temperature of substantially 600 Fahrenheit, and washing to remove the adherent salt.

ROBERT JAY SHOEMAKER.

Certificate of Correction;

It is hereby certified that in Letters Patent No. 1,533,412 3, granted ripril 14, 1025, upon the application of Robert Jay Shoemaker, of Chicago, Illinois, for an improvement in Metal-Coating Processes," an error appears in the printed specification requiring correction as follows Pa strike out all to and through the word ge manner 1, line 97 beginning with the word If line104; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Oflwe.

Signed and sealed this 23d day of June, A. D. 1925.

KARL FENNING, Acting Gammz'ssioner of Patents.

Certificate of Correction.

It is hereby certified that in Letters Patent No. 1,533,473, granted April 14, 1925, upon the application of Robert Jay Shoemaker, of Chicago, Illinois, for an improvement in Metal-Coating Processes," an error appears in the printed specification requiring correction as follows: Page 1, line 97, beginning with the word If strike out all to and through the word manner line 104; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Ofiioe.

Signed and sealed this 23d day of June, A. D. 1925.

[SEAL] KARL FENNING,

Acting Commissioner of Patents. 

